Controlled Terms or Free Terms? A JavaScript Library to Utilize Subject Headings and Thesauri on the WebIssue 15, 2011-10-31 Controlled Terms or Free Terms? A JavaScript Library to Utilize Subject Headings and Thesauri on the Web There are two types of keywords used as metadata: controlled terms and free terms. Free terms have the advantage that metadata creators can freely select keywords, but there also exists a disadvantage that the information retrieval recall ratio might be reduced. The recall
